[rocuinneagain]

For normal sorting operations see:

• https://code.kx.com/q/ref/asc/
• https://code.kx.com/q/ref/desc/

q)tab:([] sym:`a`b`c`d`e; x:5?10) q)tab sym x ----- a 8 b 1 c 9 d 5 e 4 q)`sym xdesc tab sym x ----- e 4 d 5 c 9 b 1 a 8

For your request perhaps rotate is what you are looking for

• https://code.kx.com/q/ref/rotate/

q)2 rotate tab sym x ----- c 9 d 5 e 4 a 8 b 1

 

 

[rocuinneagain]

Hi, What version of PyKX are you using?

.pykx.i.isw has been renamed to .pykx.util.isw since 2.0.0

[rocuinneagain]

Edit the file https://github.com/KxSystems/jupyterq/blob/master/kernelspec/kernel.json

{  "argv": [   "taskset",   "-c",   "0,1",   "q",   "jupyterq_kernel.q",   "-cds",   "{connection_file}"  ],  "display_name": "Q (kdb+)",  "language": "q",  "env": {"JUPYTERQ_SERVERARGS":"","MPLBACKEND":"Agg"} } 

If you have already installed you can ensure Jupyter picks up the changes by reinstalling the kernel:

python -m jupyter kernelspec install --user --name=qpk /path/to/kernelspec 

And you can validate in a notebook with system"taskset -pc ",string .z.i:

 

?

[rocuinneagain]

You have tried to use the function .arrowkdb.tb.prettyPrintTableFromTable and received the error '.arrowkdb.tb.prettyPrintTableFromTable.

In kdb this means the variable does not exist:

 

q)doesNotExist[1] 'doesNotExist [0] doesNotExist[1]

 

This suggests you have yet to load the library.

Either pass it to the command line q arrowkdb.q or load it in your running session q)l arrowkdb.q

 

[rocuinneagain]

When you download q it is included. Folder structure looks like:

kc.lic 
w64
q 
q.k

As shown on https://code.kx.com/q/learn/install/#step-3-install-the-license-file

[rocuinneagain]

Use this link: https://kx.com/download-kdb/

[rocuinneagain]

This is due to an issue with the QHOME environment variable

See: https://code.kx.com/q/learn/install/

Specifically: https://code.kx.com/q/learn/install/#step-5-edit-your-profile

setx QHOME “C:q”

Note that this points to the folder containing q.k and not to the file itself

 

[rocuinneagain]

https://code.kx.com/q/basics/errors/#:~:text=formed%20select%20query-,hop,-Request%20to%20hopen

hop

Request to hopen a handle fails; includes message from OS

Your code is trying to open a handle to a process listening on port 5001 but one is not available.

 

 

[rocuinneagain]

Yes it could be used.

 

To test you could look at PyKX for an easy Python interface.

A 2 minute example of passing in a Dataset to q in shown below.

PyKX allows Registering Custom Conversions so you could create a function to pass the Dataset in exactly the form you wish to q instead of passing it all as a dictionary in my example.

 

import pykx as kx 
import xarray as xr 
import numpy as np 
import pandas as pd 

ds = xr.Dataset(     
      {"foo": (("x", "y"), np.random.rand(5, 5))},     
      coords={         "x": [10, 20, 30, 40, 50],         
                       "y": pd.date_range("2000-01-01", periods=5),         
                       "z": ("x", list("abcde")),     }, ) 

kx.q['ds'] = kx.toq(ds.to_dict()) 

kx.q('ds') 

pykx.Dictionary(pykx.q(' 
coords   | `x`y`z!+`dims`attrs`data!((,`x;,`y;,`x);(()!();()!();()!());(10 20.. attrs    | ()!() dims     | `x`y!5 5 data_vars| (,`foo)!+`dims`attrs`data!(,`x`y;,()!();,(0.7412575 0.2054306 0.10.. ')) 

kx.q('flip ds[`coords;;`data]') 

pykx.Table(pykx.q(' 
x  y                             z 
---------------------------------- 
10 2000.01.01D00:00:00.000000000 a 
20 2000.01.02D00:00:00.000000000 b 
30 2000.01.03D00:00:00.000000000 c 
40 2000.01.04D00:00:00.000000000 d 
50 2000.01.05D00:00:00.000000000 e ')) 

kx.q('ds[`data_vars;`foo;`data]') 

pykx.List(pykx.q(' 0.7412575 0.2054306   0.1009393 0.8792678 0.04105999 0.1811459 0.01659637  0.2406029 0.4900055 0.551788   0.6303767 0.0702013   0.6831359 0.5961667 0.3722388  0.9255059 0.9202499   0.5055902 0.9767793 0.7440498  0.7331576 0.003197568 0.4939932 0.5433492 0.01175784 ')) 

 

[rocuinneagain]

You can take the old definition from the q.k file from the 2.8 version

And define it in your process with a new name:

k)wj1_28:{…

 

https://nexus.firstderivatives.com client login has downloads for versions of kdb+ including 2.8:

 KxReleases --> KDBPlus -->Releases

Some instead use: https://downloads.kx.com/

[rocuinneagain]

From 3.6 Readme

2018.09.26 NEW added -27! as a more precise, builtin version of .Q.f. n.b. It is atomic and doesn't take P into account. e.g.  q)("123456789.457";"123456790.457")~-27!(3i;0 1+2#123456789.4567)

The definition of .Q.f changed at this time also – when comparing q.k file definitions:

3.6.0 2018.09.10

f:{$[^y;"";y<0;"-",f[x;-y];y<1;1_f[x;10+y];9e15>j:"j"$y*/x#10;(x_j),".",(x:-x)#j:$j;$y]}

3.6.0 2018.10.03

f:{$[^y;"";y<0;"-",f[x;-y];y<1;1_f[x;10+y];9e15>j:"j"$y*prd x#10f;(x_j),".",(x:-x)#j:$j;$y]}

 

Floating point numbers are not exact and such behaviours should be expected in certain cases:

https://code.kx.com/q/basics/precision/

 

They are approximations:

q)P 
0 
q)4194303.975 
4194303.9750000001 
q)4194304.975 
4194304.9749999996

 

The same in C:

int main() {         double x = 4194303.975;         printf("%10.10fn",x); }

Result:

4194303.9750000001

 

If you find that you need exact decimal rounding, consider whether you actually need to operate in fixed-point, rather than floating-point.
e.g. keep monetary values in integral millicents etc.

 

 

 

[rocuinneagain]

If you have a q process which is able to use TLS then you can compare the output of it’s -26![] with the output of pykx.ssl_info[] in Python. This often shows what differences are causing the problems.

• https://code.kx.com/q/basics/internal/#-26x-ssl
• https://code.kx.com/pykx/1.6/changelog.html#pykx-140

 

[rocuinneagain]

If you have a q process which is able to use TLS then you can compare the output of it’s -26![] with the output of pykx.ssl_info[] in Python. This often shows what differences are causing the problems. – https://code.kx.com/q/basics/internal/#-26x-ssl – https://code.kx.com/pykx/1.6/changelog.html#pykx-140

[rocuinneagain]

This blog will have useful information:

Explore the methodology and benefits of kdb+ Memory Mapping | KX

[rocuinneagain]

For 3. the suggestion is to test in a browser. A q connection to the python server would fail as the protocols are different.